Design your own small power bank with this module. It can take 2-6 batteries in Parallel, and it will provide 5V 2A for its two USB outputs. It has all the safety features and characteristics that you find in any commercial power bank. You can know how much charge in the batteries from 4 on-board LEDs

SPECIFICATIONS:

• Input voltage: 4.5-8V
  
• Output voltage: continuously adjustable 4.3-27V (Counterclockwise to boost voltage)
  
• Charging voltage: 4.2V 
  
• Charging current: up to 1A
  
• Discharge current: the maximum 2A
  
• Output reference maximum current: 5V 1.4A, 9V 0.8A, 12V 0.6A
  
• Quiescent current: about 0.5 mA
  
• Overshoot protection: Yes
  
• Over discharge protection: None (also can be said yes, because 2V cut-off boost but does not block the output, output has 2V)
  
• Deadline boost:: 2V, depending on whether added the additional protection board
  
• Size: 3.3 x 2.3 x 0.9cm
  
• Connecting example, VIN connect 5V solar panel, BAT terminal can output 4.2V to charging 3.7V 18650 battery, OUT side can output an adjustable voltage